Vibrato device and stringed instrument incorporating the same



March 17, 1970 c. L. FENDER 3,500,711

VIBRATO DEVICE AND STRINGED IIIS'IRUMIEINT INCORPORATING THE SAME FiledDec. 9, 1966 3 Sheets-Sheet 1 INVENTOR. cZAPWCE z. Fat/05? March 17,1970 c. L. FENDER 3,

VIBRATO DEVICE AND STRINGED INSTRUMENT INCORPORATING THE SAME Filed Dec.9, 1966 3 Sheets-Sheet 2 INVENTOR. CZARENCE L. F'A/DEE March 17, 1970 c.L. FENDER VIBRATO DEVICE AND STRINGED INSTRUMENT INCORPORATING THE SAMEFiled Dec. 9, 1966 Sheets-Sheet 5 United States Patent 3,500,711 VIBRATODEVICE AND STRINGED INSTRUMENT INCORPORATIN G THE SAME Clarence L.Fender, Fullerton, Calif., assignor to Columbia Broadcasting System,Inc., New York, N.Y., a

corporation of New York Filed Dec. 9, 1966, Ser. No. 600,615 Int. Cl. Gd3/12 US. Cl. 84313 12 Claims ABSTRACT OF THE DISCLOSURE A vibrato devicemounted entirely above the face of the guitar includes a tail platewhich also acts as the mounting means for the vibrato. A string-engagingelement is pivotally mounted on the tail plate by a knifeedge bearing. Aleaf spring is used to counteract the pull of the strings on thestring-engaging element, and has its forward end secured to thestring-engaging element, While its rearward end is engaged by anadjustable stop means capable of varying the neutral position of thestring-engaging element.

This invention relates to a vibrator device for stringed instruments,such as hollow-body and solid-body Spanish guitars. The invention alsorelates to a guitar incorporating such vibrato device.

It is of primary importance, relative to vibrato devices for guitars andsimilar musical instruments, that the device always return to a precise,predetermined, neutral or zero position upon completion of vibratoaction. It is to be understood that the instrument is tuned when thedevice is at such zero or neutral positions, and that any deviation ofthe device from the zero position (after the guitarist releases his handfrom the device) will cause the instrument to be out of tune. Improperzeroing results from various factors, including friction, and variationsin bearing and spring characteristics. It is the belief of applicantthat the best zeroing is achieved by providing a knife-edge bearing, themembers at the knife edge being hardened, since this produces anabsolute minimum of friction and an absolute minimum of deviation ofbearing characteristics.

It is, therefore, an object of the present invention to provide avibrato device, and guitar incorporating the same, which may beconstructed to have a knife-edge bearing, with consequent substantiallyperfect zeroing.

A second important factor relative to vibrato devices is that theyshould be readily adjustable to vary the zero or neutral position. Suchadjustment may be achieved by changing the length of a lever arm,changing the bias of a spring, etc., but in any case adjustabilityshould be readily and simply achieved in order that the zero positionand other factors may be varied. One such other factor is the length ofthe vibrato excursion, on either side of the zero position, whichresults from a predetermined movement of the vibrato actuating orcontrol arm.

In view of the above, it is a further object of the present invention toprovide a vibrato device, and guitar incorporating the same, which isreadily adjustable to vary either the spring bias or the length of thelever incorporated in the vibrato, whereby the zero position and/or theexcursion from zero resulting from a predeterminated control armmovement may be readily varied.

A further factor which is important in vibrato devices is that theeffective inertia thereof be high, whereas the weight of the over-allvibrato should be kept relatively low. When the effective inertia ishigh, the com- 3,500,711 Patented Mar. 17, 1970 ponents of the vibratodo not tend to vibrate substantially in response to vibration of thestring, which vibration of the vibrato tends to damp the string actionand thus shorten the dwell time. Stated otherwise, it is desired thatnothing in the vibrato device move except in response to an intentionalshifting of the device by the hand of the musician.

It is therefore an additional object of the present invention to providea vibrato device, and guitar incorporating the same, which may beconstructed to produce a high inertia] effect, with minimum over-allweight of the device, so that desirable factors including the dwelltimes of the strings are maximized.

Base and smoothness of operation, and substantial linearity of action,are additional important factors relative to high-quality vibratodevices. It is essential that a device be readily movable by the hand ofthe guitarist, without exertion of excessive pressure and withoutsubstantial undesired pressure variations as the device moves to thevarious positions normally utilized by a guitarist.

Thus, an additional object of the present invention is to provide avibrato device, and guitar incorporating the same, which is readilyoperated and which is relatively linear in its operation throughout anormal operating range.

It should also be emphasized that a high quality commercial vibratodevice should be long lasting, simple, compact, relatively economical tomanufacture, and desirable in appearance. The various vibrato componentsmust not fatigue or wear to any substantial degree despite manythousands of vibrato movements, and despite the strong tension exertedby the strings.

Many of the above objects have previously been achieved by vibratodevices described in one or more prior patents, namely, Patents Nos.3,241,418 and 2,972,923. However, at least one very important factor Wasnot achieved by the constructions shown and described in such patents(as distinguished from constructions comprehended within the claimsthereof). Such factor relates to the ability to mount the device on aguitar, and remove the device therefrom, in a very simple manner andwithout the necessity of providing any portion of the device beneath theface of the guitar. This factor is particularly important relative tohollow-body guitars such as acoustic guitars and acoustic-electricguitars. The ability to mount a vibrato on a guitar in a minimum oftime, Without drilling holes in the face of the guitar and withoutmounting any portion of the vibrato beneath such face, is of extremeimportance in hollow-body guitars. It is also required that the vibratodevice not be bulky or unsightly.

It is therefore a further important object of the present invention toprovide a vibrato device which is mounted above the face of the guitar,such device incorporating a spring means which is low in profile and ischaracterized by a relatively small excursion so that the device doesnot appear bulky or unattractive.

Another object not achieved by the constructions shown in theabove-cited patents (as distinguished from constructions comprehendedWithin the claims thereof) is the variation of the pitches of all of thestrings by the same proportionate amount, in order that a chord beingsounded by the instrument will remain in tune during vibrato operation.

It is therefore an additional object to provide a vibrato device, andguitar, wherein chords being sounded by the strings will (for a givenset of strings) remain in tune at all times, including during thevibrato excursions.

These and other objects will become apparent from the following detaileddescription taken in connection with the accompanying drawings in which:

FIGURE 1 is a plan view of a guitar incorporating the present invention,most of the neck and some of the head being unshown in order to permitillustration of the body in larger scale;

FIGURE 2 is an enlarged vertical sectional view on line 22 of FIGURE 1;

FIGURE 3 is a further enlarged horizontal sectional view taken generallyon line 33 of FIGURE 2;

FIGURE 4 is a transverse sectional view on line 44 of FIGURE 3;

FIGURE 5 is a fragmentary sectional view taken along the broken line 5-5of FIGURE 3 and showing the vibrato device in a neutral or zeroposition;

FIGURE 6 is a view corresponding to FIGURE 5 but illustrating the deviceafter downward pressing on the control arm or handle in order to lowerthe pitches of the strings;

FIGURE 7 is a view corresponding to FIGURES 5 and 6 but illustrating thepositions of the parts following elevation of the handle in order toraise the pitches of the strings;

FIGURE 8 is a fragmentary plan view corresponding generally to the leftportion of FIGURE 3 but illustrating a second embodiment of theinvention wherein roller-type adjustment means are provided in order tovary the zero or neutral position;

FIGURE 9 is a sectional view on line 9--9 of FIGURE 8; and

FIGURE 10 is an enlarged fragmentary vertical sectional view on line1010 of FIGURE 1.

Referring first to FIGURES 1 and 2 in particular, the invention isillustrated as incorporated in a guitar which has a body 10, neck 11 andhead 12, over which are stretched a plurality (illustrated as six) ofguitar strings 13. The illustrated guitar is of the acoustic-electrictype, having a hollow body and also having an electromagnetic pickup 14which is suitably associated with an amplifier and loudspeaker, notshown.

Strings 13 are connected at one end to tuning screws 16 on head 12, andat the other end to the vibrato device 17 which forms the presentinvention. There is interposed between the vibrato device and the tuningscrews 16 a bridge 18, which should be of the pivotal or rocking varietyas will be described hereinafter. The upper or string-engaging portionof the illustrated bridge 18 may be of the general type illustrated inFIGURES et seq. of US. patent application Ser. No. 439,506, filed Feb.24, 1965, now Patent No. 3,290,980, for Bridge Constructions forGuitars. The leg portions of the bridge will be described in detailbelow.

The various elements cooperate to maintain the operative orsound-generating portions of strings 13 in generally a single planewhich is parallel to and spaced above the face of the guitar. It is tobe understood, however, that the strings may also lie along the surfaceof an imaginary large-diameter cylinder the axis of which is disposedfar below the body and is parallel to the neck. The strings aregenerally parallel to each other, although they may converge somewhat.

The hollow body 10 is illustrated in FIGURE 2 as having a face 19, back20 and tail block 21, the latter being associated with the rim, notshown. Formed in face 19 are suitable sound holes, illustrated asF-holes 22. It is emphasized that such F-holes 22 are insufiicientlylarge to facilitate mounting and demounting the vibrato components inthe interior of the body 10. Furthermore, even if the conventionalcircular sound hole of a classic guitar were present, the mounting ofcomponents within the body 10 is distinctly undesirable in a hollow-bodyguitar for various reasons including undesired variations in thegenerated sound, difficulty and expense of assembly, inability to removethe vibrato device, and the necessity of providing special internalbrace and other elements.

Proceeding next to a detailed description of the vibrato device 17, thiscomprises a tail plate 24 having two legs 25 which rest upon face 19 ina region relatively adjacent the bridge 18. The tail plate end remotefrom bridge 18 is hingedly (pivotally) secured to a hooklike mountingbracket 26, the latter being secured to tail block 21 as by theillustrated screw 27 (and/ or other screws) which may also serve as amounting button for a guitar strap. Thus, the entire vibrato device isreadily mounted on the body 10 by one or more screws 27.

As best shown in FIGURE 3, the illustrated tail plate 24 is providedwith an opening 28, the edge regions which define such openingpreferably converging in a direction toward the mounting hook 26. Theouter edges of the tail plate 24 also preferably converge toward themounting hook.

Means are provided to form a fixed bearing whereby the vibrato-connectedends of strings 13 may be pivotally moved toward and away from head 12,thus varying the string tension and creating the desired vibrato effect.Very desirably, such bearing means is of the above-mentioned knife-edgevariety, having exceedingly low friction and being substantiallyunaffected by long periods of esisting the tensioned strings.

As best shown in FIGURES 37, the knife-edge bearing means illustrated inthe drawings comprises crank or lever posts 30 which extend downwardlythrough oversize openings 31 in tail plate 24. The bottom regions of theposts 30 are annularly grooved at 32 to provide 0pposed frustoconicalgroove walls. The regions of tail plate 24 surrounding openings 31 areprovided with opposed bevels to form frustoconical surfaces which meetat an annular knife edge, a region of such knife edge belng engaged bythe apex defined between the groove walls (FIGURES 3-7). Thus, andbecause the angle between the groove walls is made larger than thatbetween the beveled frustoconical regions defining openings 31,substantially zero-friction pivotal movement is permitted between theposition shown in FIGURE 6 and that shown in FIGURE 7.

It is a feature of the illustrated, high-quality vibrato device that theconnections between posts 30 and the endS of strings 13 are made throughan inertial element 33, the latter being illustrated to comprise a solidmetal bar which extends transverse to the strings 13 and generallyparallel to the face of the guitar. Thus, the upper ends of posts 30 areshown in FIGURES 4-7 as being threadedly received withininteriorly-threaded regions of the inertial bar 33. The upper ends ofthe threaded bores are open at 34 to permit insertion of a wrench intowrench sockets 35 provided in the upper post ends. Turning of the postsby means of such a wrench varies the distance between inertial bar 33and the knife-edge bearing, thus changing the lever ratios as describedin the above-cited Patent No. 3,241,418.

The string ends are connected to the inertial element 33 in the mannershown in FIGURE 4 of said Patent 3,241,418, and extend beneath suchelement and over a portion of the bridge 18. It is pointed out that thelower edge regions of the inertial bar 33, which is preferably generallycylindrical in shape as illustrated in the drawings, is sufficiently lowthat string portions are held down against the upper surfaces of thestring-engaging bridge elements.

A vibrato-actuating handle or arm 36 is connected to inertial bar 33(preferably in the manner shown in FIG- URE 3 of said Patent 3,241,418)in order to effect pivotal movement of the bar 33 about the knife-edgehearing.

There will next be described the very important spring means foropposing the string tension and maintaining the above-indicated elementsin a precisely predetermined neutral or zero position at all timesexcept when the indicated control handle 36 is intentionally engaged andoperated by the guitarist. Such spring means is illustrated to comprisea leaf spring 38 which extends parallel to, and preferably beneath, thetail plate 24 in a direction away from the head 12 of the instrument. Asbest shown in FIGURE 3, the leaf spring 38 is generally triangular inshape, in order to achieve a substantial degree of linearity ofoperation. The opening 28 is shown as being somewhat wider than thespring, to permit upward flexing of the spring into the opening when thedevice is in oneof its pivoted positions as shown in FIGURE 6.

Means are provided to fixedly connect the wide end of spring 38 to themeans which associate the string ends with the bearing. Thus, forexample, the wide end of the spring could be connected to the lower endsof posts 30. However, in the illustrated embodiment the wide end of thespring is connected to first and second crank arms 39 (FIGURES 3 and 4)which extend downwardly into opening 28 at locations between the posts30. The crank arms are illustrated to be formed of screws 40 whichextend upwardly through spring 38 into the inertial element 33, a spacersleeve 41 being provided around each screw and seated between the springand the under side of the inertial element.

The construction of the leaf spring 38 is important to various factorsincluding ease and linearity of operation, absence of fatigue, andlimited vertical excursion in response to pivotal movement of the devicebetween the positionse of FIGURES 6 and 7. It will be understood that itis important to the appearance of the device, and other factors, thatthe spring neither engage the face 19 of the gutar body, nor exendupwardly an excessive distance, despite the pivoted position to whichthe vibrato is actuated.

The free position of the spring 38 is shown in FIGURE 7. Referring tosuch figure, and to the plan view of FIG- URE 3, the spring 38 will beseen to comprise a wide end portion 42 which extends generallyperpendicular to the crank arms 39 for a substantial distance toward thetail of the instrument. This wide end of the spring is relatively stiff,the stiffness thereof being further increased by the provision of anadditional spring element 43 therebeneath. The second spring 43 is alsoconnected to the crank arms and is generally triangular in shape asshown in FIGURE 3.

The wide, stiff base portion of the spring 38 merges through a slightangle with a long, more flexible truncated triangle 44 (forming theintermediate portion of the spring), Such triangle having edges whichconverge toward the tail of the instrument. The connection between thewide spring end 42 and the truncated triangle 44 is through a slightangle, as shown in FIGURE 7, it being understood that substantialdownward bending of that region of portion 44 which is adjacent portion42 is prevented by the stiffness of the latter and also by the lower oradditional spring 43. The apex of the lower spring 43 lies beneath thecentral region of portion 44, and is bent slightly upward.

The remaining part of the leaf spring 38 comprises a relatively narrowtongue 46 which is integrally connected with the narrow end of thetruncated triangle 44 and eX- tends upwardly therefrom at a substantialangle as shown in FIGURE 7. The tongue 46 preferably forms, as shown inFIGURE 3, an extension of the truncated triangle 44 to thus form asubstantially complete triangle thebase of which is associatedintegrally with spring end 42. The obtuse angle between the tongue 46and the truncated intermediate portion 44 of the spring, when the springis in its free position of FIGURE 7, is illustrated as being on theorder of about 160 degrees.

Adjustable stop or biasing means are provided above a region of spring38 remote from the bearing, and preferably above the tongue portion 46of the spring, to react against the tongue and thus determine (eitheralone or in conjunction with the adjustable posts 30) the neutral orzero position of the vibrato. In FIGURES 2, 3 and -7 there isillustrated an adjustable stop or biasing means which moves toward andaway from the face 19 in order to effect the adjustment. In anotherembodiment, FIG- URES 8 and 9, the adjustable means moves toward andaway from the bearing in order to effect the adjustment.

Regardless of the type of stop or biasing means for the spring regionremote from the bearing, clockwise pivotal movement of the inertialelement 33 about the knife-edge bearing effects upward flexing ofintermediate spring portion 44 (FIGURE 6), the spring then flexingupwardly into the opening 28 in the tail plate. Conversely,counterclockwise pivoting of the inertial element (FIGURE 7) causes thetongue 46 to bear only lightly against, and possibly disengage, the stoptherefor. When the device is in the neutral or zero position of FIGURE5, the intermediate spring portion 44 is slightly flexed as illustrated.

From the above it will thus be understood that the total spring movementor excursion toward and away from face 19 is small, so that the devicemay have a low profile.

Proceeding next to a detailed description of the adjustable stop orbiasing means, first embodiment, this is illustrated to comprise anangle member 47 through which an adjustment screw 48 extends and isthreaded downwardly into an interiorly threaded opening in tail plate24. A second screw 49 in the tail plate has the head thereof seatedwithin a notch 51 (FIGURE 3) between bifurcated ends of the anglemember, thus preventing pivotal movement of such member about thefirst-mentioned screw 48. The ends of element 47 remote from the bearingmeans engage the plate 24 and provide therewith a fulcrum action.

A depending end portion 52 of the angle member 47 extends downwardlyinto engagement with the upper surface of a friction-reduction member53, the latter engaging the upper surface of tongue 46. Member 53preferably comprises a strip of Teflon (polytetrafluoroethylene). TheTeflon strip may be mounted by inserting the screw 48 through a holetherein. Such strip provides a very simple and effectivefriction-reduction means, and one having characteristics which do notchange substantially with time. It is to be understood, however, that itis also within the scope of the invention to provide a roller, forexample, at the lower end of member 52, or to coat member 52 with Teflonor the like.

With the described construction, the portion of leaf spring 38 remotefrom the bearing may be elevated or depressed through an infinite numberof positions by merely turning the adjustment screw 48. For thispurpose, the head of the screw may be provided with a groove, wrenchsocket, etc., or may be adapted to be turned manually in the absence ofany tool.

Referring next to the embodiment of FIGURES 8 and 9, a roller 54 (orother suitable spring-engaging member) is mounted for shiftinglongitudinally of the instrument toward and away from the bearing.Roller 54 is shown as mounted on a slide plate 56 having an elongatedslot 57 therein through which is extended a screw 58. The screw 58 maybe turned, relative to the tail plate 24 into which it is threaded, inorder to clamp or release the slide element.

To perform an adjustment operation, it is merely necessary to loosen thescrew 58 and slide the plate 56 until roller 54 engages a differentlongitudinal position along the tongue 46 (or other portion of the leafspring). Particularly because the tongue 46 is inclined relative toplate 24, such longitudinal shifting of roller 54 changes the zero orneutral position of the vibrato device.

Because of the lever relationships present between roller 54 andinertial bar 33 (or other string-connecting member), the pressureexerted on roller 54 is only a small fraction of the pressure exerted on(for example) the roller bearings for shafts (in prior-art devices) towhich strings directly connect.

In summary, therefore, the illustrated vibrato device is in the natureof a bell crank lever having a short arm and a long arm. The short armextends from the bearing (which is preferably knife-edge) to the stringconnection element (which is preferably inertial). The long arm isresilient and preferably has associated therewith (remote from thebearing) an adjustable stop. The vibrato control arm is associated withthe short arm.

It is pointed out that the posts 30 and crank arms 39 may be replaced bya single element extending from the string connection element to thebearing.

Referring to FIGURE 4, string-receiving grooves 59 are shown as providedin the underside of inertial bar 33 (adjacent the face element 19). Eachof such grooves has a bottom wall which is generally a portion of asurface of revolution about an axis coincident with (or adjacent) theaxis of the inertial bar. The grooves 59 have different depths, whichare correlated to the characteristics of the particular strings 13 forwhich the vibrato is designed.

Because of the different depths of the grooves 59, the string portionstherein are located at different distances from the axis of pivotalmovement. Thus, a predetermined increment of pivotal movement willstretch (or relax) the strings by different amounts, which amounts arecorrelated empirically to maintain the desired tonal relationshipsbetween the strings. Therefore, for a given set of strings, the relativepitches remain constant during the vibrato action.

Proceeding next to a description of the rocking bridge 18, this has anupper section 60 which is preferably constructed in the general mannerindicated above. Referring to FIGURE 10, legs 61 are threaded upwardlyinto a casting forming the base of upper section 60, for adjustment bymeans of a wrench inserted through access holes 62. Thus, the spacing ofthe upper section 60 above the face 19 may be readily regulated.

The lower ends of legs 61 extend downwardly into oversize sockets 63formed in foot elements 64 which rest upon face 19. The lower end ofeach leg is preferably conical, and seats against the apex region of aconical bottom wall of the socket.

To maintain the elements 64 assembled with the legs during initialassembly of the guitar, and to effect centering of the legs duringmounting and adjustment of the strings, an O-ring 66 is provided in anannular g oove 67 adjacent the lower end of each leg. The O-ring bearsagainst a cylindrical region of the wall of socket 63.

The described bridge construction permits rocking or pivotal movement ofthe upper section 60 about an axis parallel to the axis of pivotalmovement of inertial element 33, so that there is no substantialfriction created by operation of the vibrato device. Furthermore, thedescribed bridge is fully adjustable and is easily assembled.

OPERATION As indicated above, the entire vibrato device is readilymounted on the guitar body 10 by merely inserting one or more screws 27through the mounting bracket 26 (FIGURE 2), the tail plate 24 then beinghingedly connected to such bracket 26 and floating on the face 19 bymeans of the legs 25. The bridge 18 may be maintained in place by stringpressure only, or the feet 44 may be adhesively or otherwise secured tothe face 19 if desired.

The illustrated vibrato may be adjusted in either or both of severalways. Thus, for example, the length of the vibrato excursion resultingfrom actuation of control handle or arm 36 through a predetermineddistance may be varied by inserting a wrench through openings 34 (FIGUREand turning the posts 30 to thus change the distance between theinertial element 33 and the bearing. This also changes the pivotedposition of the posts 30 because the length of the lever arm is changed,it being pointed out that changing of this lever arm is one way ofchanging the neutral or zero position (as described in detail in PatentNo. 3,241,418, cited above).

The zero or neutral position is also readily changed, as described indetail above, by turning the adjustment screw 48 (FIGURES 5-7) to thuschange the elevated position of the lower end of angle portion 52. Also,as described, adjustment of the spring position may be effected by theroller 54 (or equivalent element) in response to longitudinal shiftingof the slide plate 56 after screw 58 is loosened, as described relativeto FIGURES 8 and 9.

It is emphasized that the neutral or zero position of the vibrato(FIGURE 5) remains fixed at all times unless and until the screw 48 isintentionally adjusted, or the posts 30 intentionally turned. Theknife-edge contacts between the posts and the tail plate 24 at openings31 create almost no friction so that substantially the only friction inthe device is that present between the depending end 52 and the springtongue 46. The latter friction is, however, reduced to a negligibleamount by the Teflon element 53. Furthermore, such friction isinherently small because the length of element 44 provides a mechanicaladvantage which lowers the bearing pressure at portion 52.

The return to a precise zero position (after each release of controlhandle 36) is to be contrasted with various prior-art devices whereinthe bearing friction is high or wherein no true bearings are employed.It is pointed out that even the use of needle bearings, for example,does not eliminate the friction problem because the needles tend tospread (in response to long periods of string tension) and result in afalse zero or neutral position.

The linearity of operation of spring 38 is surprisingly great. Suchlinearity cooperates advantageously with what may be termed the quadranteffect which is present between the string ends and the generallycylindrical undersurfaces of inertial element 33. Referring to FIGURE 5,let it be assumed that it is desired to pivot the element 33 from theillustrated position to that shown in FIGURE 7 (counterclockwise).During the initial portion of such movement, the degree of stretching ofthe strings 13 (resulting from a predetermined amount of pivoting) willbe relatively high. However, as the FIGURE 7 position is approached, asubstantially greater amount of pivoting is required to effect apredetermined increment of stretching of the strings 13, this beingbecause the inertial element 33 is then moving largely toward the plate24 as distinguished from directly away from the head 12 of theinstrument. Stated otherwise, the more the control lever or arm 36 ispivoted counterclockwise, as the FIGURE 7 position is approached, theless stretching of the strings 13 is achieved (for a given amount ofpivoting). This creates a mechanical advantage which causes the reactionfelt by the hand of the guitarist to remain relatively uniform despiteconsiderable stretching of the stroings.

As in the case of the inertial vibrato device described in theabove-cited Patent 3,241,418, the inertial effect of element 33 isrelatively great (in comparison with the true mass thereof) because thecenter of mass of element 33 is farther from the knife-edge bearing thanare the points of engagement of the strings 13 with the underside ofelement 33. In other words, the inertial effect is multiplied by thelever relationship. This inertial eifect is important to thehighest-quality vibrato action since it minimizes the vibration of thevibrato and thus maximizes the dwell of the strings. It is pointed out,however, that the inertial element 33 may be omitted while stillretaining certain important aspects of the present invention.

Guitarists conventionally desire to effect flatting of the strings inresponse to depression of the handle 36 when the handle is in theposition shown in FIGURE 1. This is effected automatically by the leverrelationship described herein, and renders unnecessary the provision ofextra rollers (with resulting additional friction) such as are requiredon some vibratos. The additional rollers provided on some prior-artvibrato devices are also undesirable in that additional friction iscreated due to differential (or varying) stretching of the stringsduring the vibrato act1on.

As stated heretofore, with particular reference to FIG URE 4, thegrooves 59 in element 33 operate to maintain the tuning (of a givenclass of strings) during vibrato action. Such grooves may, however, beomitted if desired.

The described construction of the leaf spring 38 not only producesrelatively linear action, but also minimizes fatigue in that very littlebending occurs in a region adjacent the bearing. Thus, the leaf springis very long lasting and dependable.

The use of the term leaf spring in the present specification and in theappended claims does not necessarily denote that more than one spring isemployed (although two or more may be used). Such term is primarilyintended to distinguish from torsion springs, helical springs, etc.

The present vibrato device is capable of relatively wide vibratoexcusions, yet the leaf spring is so constructed that even such wideexcursions do not create excessive fatigue of the spring, or excessivenon-linearity of operation.

It is a feature of the present vibrato that the inertial element 33 canbe located relatively near the bridge 18. This creates maximum variationin tone in response to a given degree of pivoting. It will be understoodthat if the vibrato were far from the bridge, much of the stringstretching would occur in the inoperative string portions (between thebridge and bar 33).

I claim:

1. A vibrato device for a guitar or similar musical instrument, whichcomprises:

a mounting element adapted to be mounted over the face of a guitar body,

a string-connecting element adapted to be connected to a plurality ofguitar strings,

a bearing to pivotally associate said mounting element andstring-connecting element with each other for pivotal movement of saidstring-connecting element about an axis transverse to said strings,

said bearing being a knife-edge bearing between said string-connectingelement and said mounting element,

leaf spring means operatively associated with said string-connectingelement to counterbalance the tension of said strings and maintain saidstring-connecting element in a predetermined desired neutral position,and

means to pivot said string-connecting element about said axis to thusalternately tension and relax said strings and probide a vibrato effect.

2. A vibrato device adapted to be mounted entirely above the fact of aguitar or similar musical instrument, which comprises:

a tail plate adapted to be mounted over the face of a guitar bodyadjacent the tail thereof,

a string-connecting element mounted on the opposite side of said tailplate from said face,

said string-connecting element being a high-inertia bar extendingparallel to said tail plate and spaced thereabove,

a bearing pivotally associating said tail plate with said bar to therebypermit pivotal movement of said bar about an axis parallel to said faceand transverse to the strings of the guitar,

said guitar strings extending beneath said bar,

the underside of said bar being rounded about an axis generally parallelto said axis of pivotal movement,

said underside of said bar being spaced a substantial distance fartherfrom said face than is said axis of pivotal movement,

a leaf spring operably associated with said bar and extending generallyparallel to said tail plate,

said leaf spring being also operably associated with said tail plate andhaving such characteristics that said bar is maintained by said leafspring in a neutral position at all times except when 10 said bar isintentionally pivoted about said axis, and

means to effect pivoting of said bar about said axis to therebyalternately tension and relax said guitar strings and provide a vibratoeffect.

3. A vibrato device adapted to be mounted entirely above the face of aguitar or similar musical instrument, 'which comprises:

a tail plate adapted to be mounted over the face of a guitar bodyadjacent the tail thereof,

a string-connecting element mounted on the opposite side of said tailplate from said face,

a bearing pivotally associating said tail plate with saidstring-connecting element to thereby permit pivotal movement of saidstring-connecting element about an axis parallel to said face andtransverse to the Strings of the guitar,

posts extended downwardly from said string-connecting element to saidtail plate,

said posts having annular grooves therein whereby the grooved regions ofsaid posts may engage said tail plate at edges thereof defining openingstherein to form said bearing,

said edges having sharp knife-edge regions to thus minimize frictionwhen said posts pivot thereagainst,

a leaf spring operably associated with said string-connecting elementand extending generally parallel to said tail plate,

said leaf spring being also operably associated with said tail plate andhaving such characteristics that said string-connecting element ismaintained by said leaf spring in a neutral position at all times exceptwhen said string-connecting element is intentionally pivoted about saidaxis, and

means to effect pivoting of said string-connecting element about saidaxis to thereby tension and relax the guitar strings and provide avibrato effect.

4. The invention as claimed in claim 3, in which said posts are threadedinto said string-connecting element, and in which means are provided torotate said posts to thereby vary the distance between saidstring-connecting element and said knife-edge regions.

5. A vibrato device adapted to be mounted entirely above the face of aguitar or similar musical instrument, which comprises:

a tail plate adapted to be mounted over the face of a guitar bodyadjacent the tail thereof,

a string-connecting element mounted on the opposite side of said tailplate from said face,

a bearing pivotally associating said tail plate with saidstring-connecting element to thereby permit pivotal movement of saidstring-connecting element about an axis parallel to said face andtransverse to the strings of the guitar,

a leaf spring operably associated with said string-connecting elementand extending generally parallel to said tail plate,

said leaf spring being also operably associated with said tail plate andhaving such characteristics that said string-connecting element ismaintained by said leaf spring in a neutral position at all times exceptwhen said string-connecting element is intentionally pivoted about saidaxis, adjustment means provided on said tail plate to bear against aregion of said leaf spring remote from said bearing,

said adjustment means being adjustable to determine the neutral positionof said spring and of said string-connecting element, and

means to effect pivoting of said string-connecting element about saidaxis to thereby tension and relax the guitar strings and provide avibrato effect.

6. The invention as claimed in claim 5, in which said adjustment meanscomprises means to effect adjustment of said spring region in directionstoward and away from said face.

7. The invention as claimed in claim 5, in which said adjustment meansmoves in directions toward and away from said bearing, and in which saidleaf spring is inclined whereby said adjustment toward and away fromsaid bearing effects adjustment of the initial position of said spring.

8. The invention as claimed in claim 5, in which friction-minimizingmaterial is interposed between said adjustment means and said region ofsaid spring.

9. A vibrato device adapted to be mounted entirely above the face of aguitar or similar musical instrument, which comprises:

a tail plate adapted to be mounted over the face of a guitar bodyadjacent the tail thereof,

a string-connecting element mounted on the opposite side of said tailplate from said face,

a bearing pivotally associating said tail plate with saidstring-connecting element to thereby permit pivotal movement of saidstring-connecting element about an axis parallel tosaid face andtransverse to the strings of the guitar,

a leaf spring operably associated with said string-connecting elementand extending generally parallel to said tail plate,

said leaf spring being also operably associated with said tail plate andhaving such characteristics that said string-connecting element ismaintained by said leaf spring in a neutral position at all times exceptwhen said string-connecting element is intentionally pivoted about saidaxis,

said leaf spring being connected to said stringconnecting element bycrank means which extends to said string-connecting elementindependently of said bearing, and

means to effect pivoting of said string-connecting element about saidaxis to thereby tension and relax the guitar strings and provide avibrato effect.

10. A vibrato device, which comprises:

a lever having a short arm,

said lever also having a long arm at least a portion of which isresilient whereby said long arm may be flexed,

means to mount said lever on a guitar body,

said means including a bearing element adapted to permit pivotalmovement of said lever about a predetermined axis, said means mountingsaid lever in such position that said long arm is generally parallel tothe face of said guitar body and is above said face, means to connectsaid short arm to the strings of said guitar and in such manner that thetension of said strings tends to pivot said lever in a predetermineddirection about said axis,

stop means associated with said long arm, at a region thereof remotefrom said axis, to oppose pivotal movement of said long arm in saidpredetermined direction and responsive to said string tension,

said stop means being unconnected to said long arm, and

manually-operated means to pivot said lever about said axis to thustension and relax said strings and provide a vibrato effect,

said long arm flexing during said vibrato action and serving upontermination thereof to return said connecting means to a predeterminedneutral position.

11. A vibrato device adapted to be mounted entirely above the face of aguitar or similar musical instrument, which comprises:

an elongated tail plate,

means to mount said tail plate generally parallel to and above the faceof a guitar body relatively adjacent the tail thereof,

a string-connecting element mounted on the opposite side of said tailplate from said face,

a bearing pivotally associating said tail plate with saidstring-connecting element to thereby permit pivotal movement of saidstring-connecting element about an axis parallel to said face andtransverse to the strings of the guitar,

said bearing being interposed between said stringconnecting element andsaid tail plate whereby the tension of said strings is borne by saidbearing,

an elongated flexible spring operably associated with saidstring-connecting element and extending generally parallel to andbeneath said tail plate,

said spring being also operably associated with said tail plate andhaving such characteristics that said string-connecting element ismaintained by said spring in a neutral position at all times except whensaid string-connecting element is intentionally pivoted about said axis,and

means to effect pivoting of said string-connecting element about saidaxis to thereby tension and relax the guitar strings and provide avibrato effect.

12. A vibrato device adapted to be mounted entirely above the face of aguitar or similar musical instrument, which comprises:

a tail plate adapted to be mounted over the face of a guitar bodyadjacent the tail thereof,

a string-connecting element mounted on the opposite side of said tailplate from said face,

said string-connecting element having a high mass,

a bearing pivotally associating said tail plate with saidstring-connecting element to thereby permit pivotal movement of saidstring-connecting element about an axis parallel to said face andtransverse to the strings of the guitar,

said bearing being a knife-edge bearing,

said bearing being interposed between said stringconnecting element andsaid tail plate whereby the tension of said strings is borne by saidbearing,

an elongated flexible spring operably associated with saidstring-connecting element and extending generally parallel to andbeneath said tail plate,

said spring being also operably associated with said tail plate andhaving such characteristics that said string-connecting element ismaintained by said spring in a neutral position at all times except whensaid string-connecting element is intentionally pivoted about said axis,and

means to effect pivoting of said string-connecting element about saidaxis to thereby tension and relax the guitar strings and provide avibrato effect.

References Cited UNITED STATES PATENTS 1,775,089 9/1930 De Costa 84313 X3,056,329 10/1962 Butts 84-313 3,124,991 3/1964 Costen 84313 X 3,142,2217/1964 Boyd 843 13 3,174,381 3/1965 Matthew et al 84313 3,241,418 3/1966Fender 84-313 3,290,980 12/1966 Fender 843 13 RICHARD B. WILKINSON,Primary Examiner J. F. GONZALES, Assistant Examiner

